/* GIF reading routines based on those in pbmplus:ppm/giftoppm.c, bearing
 * following copyright notice:
 */

/* +-------------------------------------------------------------------+ */
/* | Copyright 1990, David Koblas.                                     | */
/* |   Permission to use, copy, modify, and distribute this software   | */
/* |   and its documentation for any purpose and without fee is hereby | */
/* |   granted, provided that the above copyright notice appear in all | */
/* |   copies and that both that copyright notice and this permission  | */
/* |   notice appear in supporting documentation.  This software is    | */
/* |   provided "as is" without express or implied warranty.           | */
/* +-------------------------------------------------------------------+ */


#include "config.h"
#include "tile.h"

#ifndef MONITOR_HEAP
extern long *FDECL(alloc, (unsigned int));
#endif

#define PPM_ASSIGN(p,red,grn,blu) do { (p).r = (red); (p).g = (grn); (p).b = (blu); } while ( 0 )

#define	MAX_LWZ_BITS		12

#define INTERLACE		0x40
#define LOCALCOLORMAP	0x80
#define BitSet(byte, bit)	(((byte) & (bit)) == (bit))

#define	ReadOK(file,buffer,len)	(fread((genericptr_t)buffer, (int)len, 1, file) != 0)

#define LM_to_uint(a,b)			(((b)<<8)|(a))

struct gifscreen {
	int	Width;
	int	Height;
	int	Colors;
	int	ColorResolution;
	int	Background;
	int	AspectRatio;
	int	Interlace;
} GifScreen;

struct {
	int	transparent;
	int	delayTime;
	int	inputFlag;
	int	disposal;
} Gif89 = { -1, -1, -1, 0 };

int	ZeroDataBlock = FALSE;

static FILE *gif_file;
static int tiles_across, tiles_down, curr_tiles_across, curr_tiles_down;
static pixel **image;
static unsigned char input_code_size;

static int FDECL(GetDataBlock, (FILE *fd, unsigned char *buf));
static void FDECL(DoExtension, (FILE *fd, int label));
static boolean FDECL(ReadColorMap, (FILE *fd, int number));
static void FDECL(read_header, (FILE *fd));
static int FDECL(GetCode, (FILE *fd, int code_size, int flag));
static int FDECL(LWZReadByte, (FILE *fd, int flag, int input_code_size));
static void FDECL(ReadInterleavedImage, (FILE *fd, int len, int height));
static void FDECL(ReadTileStrip, (FILE *fd, int len));

/* These should be in gif.h, but there isn't one. */
boolean FDECL(fopen_gif_file, (const char *, const char *));
boolean FDECL(read_gif_tile, (pixel(*)[]));
int NDECL(fclose_gif_file);

static int
GetDataBlock(fd, buf)
FILE		*fd;
unsigned char	*buf;
{
	unsigned char	count;

	if (!ReadOK(fd,&count,1)) {
		Fprintf(stderr, "error in getting DataBlock size\n");
		return -1;
	}

	ZeroDataBlock = (count == 0);

	if ((count != 0) && (!ReadOK(fd, buf, count))) {
		Fprintf(stderr, "error in reading DataBlock\n");
		return -1;
	}

	return count;
}

static void
DoExtension(fd, label)
FILE	*fd;
int	label;
{
	static char	buf[256];
	char		*str;

	switch (label) {
	case 0x01:		/* Plain Text Extension */
		str = "Plain Text Extension";
#ifdef notdef
		if (GetDataBlock(fd, (unsigned char*) buf) == 0)
			;

		lpos   = LM_to_uint(buf[0], buf[1]);
		tpos   = LM_to_uint(buf[2], buf[3]);
		width  = LM_to_uint(buf[4], buf[5]);
		height = LM_to_uint(buf[6], buf[7]);
		cellw  = buf[8];
		cellh  = buf[9];
		foreground = buf[10];
		background = buf[11];

		while (GetDataBlock(fd, (unsigned char*) buf) != 0) {
			PPM_ASSIGN(image[ypos][xpos],
					cmap[CM_RED][v],
					cmap[CM_GREEN][v],
					cmap[CM_BLUE][v]);
			++index;
		}

		return;
#else
		break;
#endif
	case 0xff:		/* Application Extension */
		str = "Application Extension";
		break;
	case 0xfe:		/* Comment Extension */
		str = "Comment Extension";
		while (GetDataBlock(fd, (unsigned char*) buf) != 0) {
			Fprintf(stderr, "gif comment: %s\n", buf );
		}
		return;
	case 0xf9:		/* Graphic Control Extension */
		str = "Graphic Control Extension";
		(void) GetDataBlock(fd, (unsigned char*) buf);
		Gif89.disposal    = (buf[0] >> 2) & 0x7;
		Gif89.inputFlag   = (buf[0] >> 1) & 0x1;
		Gif89.delayTime   = LM_to_uint(buf[1],buf[2]);
		if ((buf[0] & 0x1) != 0)
			Gif89.transparent = buf[3];

		while (GetDataBlock(fd, (unsigned char*) buf) != 0)
			;
		return;
	default:
		str = buf;
		Sprintf(buf, "UNKNOWN (0x%02x)", label);
		break;
	}

	Fprintf(stderr, "got a '%s' extension\n", str);

	while (GetDataBlock(fd, (unsigned char*) buf) != 0)
		;
}

static
boolean
ReadColorMap(fd,number)
FILE		*fd;
int		number;
{
	int		i;
	unsigned char	rgb[3];

	for (i = 0; i < number; ++i) {
		if (!ReadOK(fd, rgb, sizeof(rgb))) {
			return(FALSE);
		}

		ColorMap[CM_RED][i] = rgb[0] ;
		ColorMap[CM_GREEN][i] = rgb[1] ;
		ColorMap[CM_BLUE][i] = rgb[2] ;
	}
	colorsinmap = number;
	return TRUE;
}

/*
 * Read gif header, including colormaps.  We expect only one image per
 * file, so if that image has a local colormap, overwrite the global one.
 */
static void
read_header(fd)
FILE	*fd;
{
	unsigned char	buf[16];
	unsigned char	c;
	char		version[4];

	if (!ReadOK(fd,buf,6)) {
		Fprintf(stderr, "error reading magic number\n");
		exit(EXIT_FAILURE);
	}

	if (strncmp((genericptr_t)buf,"GIF",3) != 0) {
		Fprintf(stderr, "not a GIF file\n");
		exit(EXIT_FAILURE);
	}

	(void) strncpy(version, (char *)buf + 3, 3);
	version[3] = '\0';

	if ((strcmp(version, "87a") != 0) && (strcmp(version, "89a") != 0)) {
		Fprintf(stderr, "bad version number, not '87a' or '89a'\n");
		exit(EXIT_FAILURE);
	}

	if (!ReadOK(fd,buf,7)) {
		Fprintf(stderr, "failed to read screen descriptor\n");
		exit(EXIT_FAILURE);
	}

	GifScreen.Width           = LM_to_uint(buf[0],buf[1]);
	GifScreen.Height          = LM_to_uint(buf[2],buf[3]);
	GifScreen.Colors          = 2<<(buf[4]&0x07);
	GifScreen.ColorResolution = (((buf[4]&0x70)>>3)+1);
	GifScreen.Background      = buf[5];
	GifScreen.AspectRatio     = buf[6];

	if (BitSet(buf[4], LOCALCOLORMAP)) {	/* Global Colormap */
		if (!ReadColorMap(fd, GifScreen.Colors)) {
			Fprintf(stderr, "error reading global colormap\n");
			exit(EXIT_FAILURE);
		}
	}

	if (GifScreen.AspectRatio != 0 && GifScreen.AspectRatio != 49) {
		Fprintf(stderr, "warning - non-square pixels\n");
	}

	for (;;) {
		if (!ReadOK(fd,&c,1)) {
			Fprintf(stderr, "EOF / read error on image data\n");
			exit(EXIT_FAILURE);
		}

		if (c == ';') {		/* GIF terminator */
			return;
		}

		if (c == '!') {		/* Extension */
		    if (!ReadOK(fd,&c,1)) {
			Fprintf(stderr,
			    "EOF / read error on extension function code\n");
			exit(EXIT_FAILURE);
		    }
		    DoExtension(fd, (int)c);
		    continue;
		}

		if (c != ',') {		/* Not a valid start character */
			Fprintf(stderr,
				"bogus character 0x%02x, ignoring\n", (int) c);
			continue;
		}

		if (!ReadOK(fd,buf,9)) {
		    Fprintf(stderr, "couldn't read left/top/width/height\n");
		    exit(EXIT_FAILURE);
		}

		if (BitSet(buf[8], LOCALCOLORMAP)) {
			/* replace global color map with local */
			GifScreen.Colors = 1<<((buf[8]&0x07)+1);
			if (!ReadColorMap(fd, GifScreen.Colors)) {
			    Fprintf(stderr, "error reading local colormap\n");
			    exit(EXIT_FAILURE);
			}

		}
		if (GifScreen.Width != LM_to_uint(buf[4],buf[5])) {
			Fprintf(stderr, "warning: widths don't match\n");
			GifScreen.Width = LM_to_uint(buf[4],buf[5]);
		}
		if (GifScreen.Height != LM_to_uint(buf[6],buf[7])) {
			Fprintf(stderr, "warning: heights don't match\n");
			GifScreen.Height = LM_to_uint(buf[6],buf[7]);
		}
		GifScreen.Interlace = BitSet(buf[8], INTERLACE);
		return;
	}
}

static int
GetCode(fd, code_size, flag)
FILE	*fd;
int	code_size;
int	flag;
{
	static unsigned char	buf[280];
	static int		curbit, lastbit, done, last_byte;
	int			i, j, ret;
	unsigned char		count;

	if (flag) {
		curbit = 0;
		lastbit = 0;
		done = FALSE;
		return 0;
	}

	if ((curbit+code_size) >= lastbit) {
		if (done) {
			if (curbit >= lastbit)
				Fprintf(stderr, "ran off the end of my bits\n");
			return -1;
		}
		buf[0] = buf[last_byte-2];
		buf[1] = buf[last_byte-1];

		if ((count = GetDataBlock(fd, &buf[2])) == 0)
			done = TRUE;

		last_byte = 2 + count;
		curbit = (curbit - lastbit) + 16;
		lastbit = (2+count)*8 ;
	}

	ret = 0;
	for (i = curbit, j = 0; j < code_size; ++i, ++j)
		ret |= ((buf[ i / 8 ] & (1 << (i % 8))) != 0) << j;

	curbit += code_size;

	return ret;
}

static int
LWZReadByte(fd, flag, input_code_size)
FILE	*fd;
int	flag;
int	input_code_size;
{
	static int	fresh = FALSE;
	int		code, incode;
	static int	code_size, set_code_size;
	static int	max_code, max_code_size;
	static int	firstcode, oldcode;
	static int	clear_code, end_code;
	static int	table[2][(1<< MAX_LWZ_BITS)];
	static int	stack[(1<<(MAX_LWZ_BITS))*2], *sp;
	register int	i;

	if (flag) {
		set_code_size = input_code_size;
		code_size = set_code_size+1;
		clear_code = 1 << set_code_size ;
		end_code = clear_code + 1;
		max_code_size = 2*clear_code;
		max_code = clear_code+2;

		(void) GetCode(fd, 0, TRUE);

		fresh = TRUE;

		for (i = 0; i < clear_code; ++i) {
			table[0][i] = 0;
			table[1][i] = i;
		}
		for (; i < (1<<MAX_LWZ_BITS); ++i)
			table[0][i] = table[1][0] = 0;

		sp = stack;

		return 0;
	} else if (fresh) {
		fresh = FALSE;
		do {
			firstcode = oldcode = GetCode(fd, code_size, FALSE);
		} while (firstcode == clear_code);
		return firstcode;
	}

	if (sp > stack)
		return *--sp;

	while ((code = GetCode(fd, code_size, FALSE)) >= 0) {
		if (code == clear_code) {
			for (i = 0; i < clear_code; ++i) {
				table[0][i] = 0;
				table[1][i] = i;
			}
			for (; i < (1<<MAX_LWZ_BITS); ++i)
				table[0][i] = table[1][i] = 0;
			code_size = set_code_size+1;
			max_code_size = 2*clear_code;
			max_code = clear_code+2;
			sp = stack;
			firstcode = oldcode = GetCode(fd, code_size, FALSE);
			return firstcode;
		} else if (code == end_code) {
			int		count;
			unsigned char	buf[260];

			if (ZeroDataBlock)
				return -2;

			while ((count = GetDataBlock(fd, buf)) > 0)
				;

			if (count != 0)
			    Fprintf(stderr,
			    "missing EOD in data stream (common occurrence)\n");
			return -2;
		}

		incode = code;

		if (code >= max_code) {
			*sp++ = firstcode;
			code = oldcode;
		}

		while (code >= clear_code) {
			*sp++ = table[1][code];
			if (code == table[0][code]) {
			    Fprintf(stderr, "circular table entry BIG ERROR\n");
			    exit(EXIT_FAILURE);
			}
			code = table[0][code];
		}

		*sp++ = firstcode = table[1][code];

		if ((code = max_code) <(1<<MAX_LWZ_BITS)) {
			table[0][code] = oldcode;
			table[1][code] = firstcode;
			++max_code;
			if ((max_code >= max_code_size) &&
				(max_code_size < (1<<MAX_LWZ_BITS))) {
				max_code_size *= 2;
				++code_size;
			}
		}

		oldcode = incode;

		if (sp > stack)
			return *--sp;
	}
	return code;
}


static void
ReadInterleavedImage(fd, len, height)
FILE	*fd;
int	len, height;
{
	int		v;
	int		xpos = 0, ypos = 0, pass = 0;

	while ((v = LWZReadByte(fd,FALSE,(int)input_code_size)) >= 0 ) {
		PPM_ASSIGN(image[ypos][xpos], ColorMap[CM_RED][v],
				ColorMap[CM_GREEN][v], ColorMap[CM_BLUE][v]);

		++xpos;
		if (xpos == len) {
			xpos = 0;
			switch (pass) {
				case 0:
				case 1:
					ypos += 8; break;
				case 2:
					ypos += 4; break;
				case 3:
					ypos += 2; break;
			}

			if (ypos >= height) {
				++pass;
				switch (pass) {
					case 1:
						ypos = 4; break;
					case 2:
						ypos = 2; break;
					case 3:
						ypos = 1; break;
					default:
						goto fini;
				}
			}
		}
		if (ypos >= height)
			break;
	}

fini:
	if (LWZReadByte(fd,FALSE,(int)input_code_size)>=0)
		Fprintf(stderr, "too much input data, ignoring extra...\n");
}

static
void
ReadTileStrip(fd,len)
FILE *fd;
int len;
{
	int	v;
	int	xpos = 0, ypos = 0;

	while ((v = LWZReadByte(fd,FALSE,(int)input_code_size)) >= 0 ) {
		PPM_ASSIGN(image[ypos][xpos], ColorMap[CM_RED][v],
				ColorMap[CM_GREEN][v], ColorMap[CM_BLUE][v]);

		++xpos;
		if (xpos == len) {
			xpos = 0;
			++ypos;
		}
		if (ypos >= TILE_Y)
			break;
	}
}




boolean
fopen_gif_file(filename, type)
const char *filename;
const char *type;
{
	int i;

	if (strcmp(type, RDBMODE)) {
		Fprintf(stderr, "using reading routine for non-reading?\n");
		return FALSE;
	}
	gif_file = fopen(filename, type);
	if (gif_file == (FILE *)0) {
		Fprintf(stderr, "cannot open gif file %s\n", filename);
		return FALSE;
	}

	read_header(gif_file);
	if (GifScreen.Width % TILE_X) {
		Fprintf(stderr, "error: width %d not divisible by %d\n",
				GifScreen.Width, TILE_X);
		exit(EXIT_FAILURE);
	}
	tiles_across = GifScreen.Width / TILE_X;
	curr_tiles_across = 0;
	if (GifScreen.Height % TILE_Y) {
		Fprintf(stderr, "error: height %d not divisible by %d\n",
				GifScreen.Height, TILE_Y);
		/* exit(EXIT_FAILURE) */;
	}
	tiles_down = GifScreen.Height / TILE_Y;
	curr_tiles_down = 0;

	if (GifScreen.Interlace) {
	    /* sigh -- hope this doesn't happen on micros */
	    image = (pixel **)alloc(GifScreen.Height * sizeof(pixel *));
	    for (i = 0; i < GifScreen.Height; i++) {
		image[i] = (pixel *) alloc(GifScreen.Width * sizeof(pixel));
	    }
	} else {
	    image = (pixel **)alloc(TILE_Y * sizeof(pixel *));
	    for (i = 0; i < TILE_Y; i++) {
		image[i] = (pixel *) alloc(GifScreen.Width * sizeof(pixel));
	    }
	}

	/*
	**  Initialize the Compression routines
	*/
	if (!ReadOK(gif_file,&input_code_size,1)) {
		Fprintf(stderr, "EOF / read error on image data\n");
		exit(EXIT_FAILURE);
	}

	if (LWZReadByte(gif_file, TRUE, (int)input_code_size) < 0) {
		Fprintf(stderr, "error reading image\n");
		exit(EXIT_FAILURE);
	}

	/* read first section */
	if (GifScreen.Interlace) {
		ReadInterleavedImage(gif_file,
					GifScreen.Width,GifScreen.Height);
	} else {
		ReadTileStrip(gif_file,GifScreen.Width);
	}
	return TRUE;
}

/* Read a tile.  Returns FALSE when there are no more tiles */
boolean
read_gif_tile(pixels)
pixel (*pixels)[TILE_X];
{
	int i, j;

	if (curr_tiles_down >= tiles_down) return FALSE;
	if (curr_tiles_across == tiles_across) {
		curr_tiles_across = 0;
		curr_tiles_down++;
		if (curr_tiles_down >= tiles_down) return FALSE;
		if (!GifScreen.Interlace)
			ReadTileStrip(gif_file,GifScreen.Width);
	}
	if (GifScreen.Interlace) {
		for (j = 0; j < TILE_Y; j++) {
		    for (i = 0; i < TILE_X; i++) {
			pixels[j][i] = image[curr_tiles_down*TILE_Y + j]
					    [curr_tiles_across*TILE_X + i];
		    }
		}
	} else {
		for (j = 0; j < TILE_Y; j++) {
		    for (i = 0; i < TILE_X; i++) {
			pixels[j][i] = image[j][curr_tiles_across*TILE_X + i];
		    }
		}
	}
	curr_tiles_across++;

	/* check for "filler" tile */
	for (j = 0; j < TILE_Y; j++) {
		for (i = 0; i < TILE_X && i < 4; i += 2) {
			if (pixels[j][i].r != ColorMap[CM_RED][0] ||
			    pixels[j][i].g != ColorMap[CM_GREEN][0] ||
			    pixels[j][i].b != ColorMap[CM_BLUE][0] ||
			    pixels[j][i+1].r != ColorMap[CM_RED][1] ||
			    pixels[j][i+1].g != ColorMap[CM_GREEN][1] ||
			    pixels[j][i+1].b != ColorMap[CM_BLUE][1])
				return TRUE;
		}
	}
	return FALSE;
}

int
fclose_gif_file()
{
	int i;

	if (GifScreen.Interlace) {
		for (i = 0; i < GifScreen.Height; i++) {
			free((genericptr_t)image[i]);
		}
		free((genericptr_t)image);
	} else {
		for (i = 0; i < TILE_Y; i++) {
			free((genericptr_t)image[i]);
		}
		free((genericptr_t)image);
	}
	return(fclose(gif_file));
}

#ifndef AMIGA
static char *std_args[] = { "tilemap",	/* dummy argv[0] */
			"monsters.gif", "monsters.txt",
			"objects.gif",  "objects.txt",
			"other.gif",    "other.txt" };

int
main(argc, argv)
int argc;
char *argv[];
{
	pixel pixels[TILE_Y][TILE_X];

	if (argc == 1) {
		argc = SIZE(std_args);
		argv = std_args;
	} else if (argc != 3) {
		Fprintf(stderr, "usage: gif2txt giffile txtfile\n");
		exit(EXIT_FAILURE);
	}

	while (argc > 1) {
		if (!fopen_gif_file(argv[1], RDBMODE))
			exit(EXIT_FAILURE);

		init_colormap();

		if (!fopen_text_file(argv[2], WRTMODE)) {
			(void) fclose_gif_file();
			exit(EXIT_FAILURE);
		}

		while (read_gif_tile(pixels))
			(void) write_text_tile(pixels);

		(void) fclose_gif_file();
		(void) fclose_text_file();

		argc -= 2;
		argv += 2;
	}
	exit(EXIT_SUCCESS);
	/*NOTREACHED*/
	return 0;
}
#endif
